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How to Speed Up the Addition of ISDN B Channels to a Multilink PPP Bundle

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Document ID: 10240


Contents

Introduction
Prerequisites
      Requirements
      Components Used
      Conventions
Commands to Use
Related Information

Introduction

This document provides a list of commands you can use to add ISDN B channels to a Multilink Point-to-Point Protocol (PPP) bundle more quickly.

Prerequisites

Requirements

There are no specific requirements for this document.

Components Used

The information in this document is based on these software and hardware versions:

  • Cisco IOS® Software Releases 11.3(2.1) and later.

The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.

Conventions

For more information on document conventions, refer to the Cisco Technical Tips Conventions.

Commands to Use

In a Primary Rate Interface (PRI), it is often desirable to add Integrated Services Digital Network (ISDN) B channels as quickly as possible. If Multilink PPP is configured in the PRI interface, the following commands allow you to add B channels to the Multilink bundle more quickly:

  • dialer load-threshold 1 — Sets the load-threshold to the minimum possible value. This ways, another link is added to the multilink bundle as soon as the load reaches the minimum threshold (1/255).

  • load-interval 30 — Increases the frequency of the interface load calculation. By default, the interface load is calculated as an exponential average over the last five minutes. By setting the load-interval parameter to 30 seconds, you force a more frequent calculation of the interface load. This results in an earlier detection of changes in the interface load. By shortening the length of time during which you compute the interface load, you also shorten the time required to bring up additional B channels because the router will detect an increase of the interface load sooner.

  • ppp timeout multilink link add <seconds> — Sets the time required to add another link to the multilink bundle.

    This timer determines how long PPP multilink waits after adding a link to the bundle before adding additional links due to the load threshold being exceeded. The minimum possible value is 1 second. The default is 30 seconds.

    Note: This setting only applies when PPP multilink adds the third and subsequent links to the bundle. If you use a software version earlier than Cisco IOS Software Release 11.3(2.1), the command to use for this task is dialer wait-for-carrier <seconds> .

Related Information

Updated: Sep 09, 2005 Document ID: 10240